Will a Sigma 150-500mm f/5-6.3 APO DG HSM autofocus on a Nikon D5500?

Asked 6/7/2016

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I have a Sigma 150-500mm f/5-6.3 APO DG HSM that autofocuses on my Nikon D40X, but on a Nikon D5500 it switches inconsistently between AF and MF and autofocus is unreliable. Should this lens autofocus on the D5500, and if not, is this more likely to be a compatibility/firmware issue or just low-light focusing difficulty at the lens's f/6.3 maximum aperture?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

10y ago

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It appears you are shooting indoors. At f/6.3 there's probably not enough edge light making it through the lens to the camera's AF sensor for the camera focus the lens. If you were in brighter conditions or aiming at very high contrast targets it might work better. The PDAF sensor in any SLR with AF compares edge light from opposite sides of the lens to measure focus.

One of the conundrums facing camera designers is whether to optimize a PDAF system to work with narrower aperture lenses (but with less accuracy due to the narrower baseline of the focus sensor's elements for their positions on opposite sides of the lens) or to optimize it with a wider baseline that can take advantage of wider aperture lenses that allow it to be more accurate and work in dimmer light when used with a wide aperture lens. These wider pairs of lines on the AF sensor won't work at all with lenses too narrow, though.

Some cameras hedge their bets a little: some focus sensor lines are optimized for narrower apertures and others are optimized for wider apertures. When used with a narrower aperture lens, the points sensitive at f/5.6 or f/8 will provide some functionality. When used with wider aperture lenses the points sensitive only at or below f/4 or even f/2.8 will provide more accurate autofocus.

Your D40X is probably designed for all AF points to be usable with lenses up to maximum apertures as small as f/8. Most Nikon AF systems at that time were. Your newer D5500 is probably designed to be usable with lenses having a maximum aperture of f/5.6 or wider.

Switching to Live View might allow the image sensor's CDAF to focus, but there's no guarantee the lens' narrow maximum aperture of f/6.3 won't give the CDAF of the image sensor problems as well.

Originally by user15871. Source · Licensed CC BY-SA 4.0

user15871

10y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

Yes, this lens should be able to autofocus on a Nikon D5500, but two issues can make it seem unreliable.

First, at the long end the lens is only f/6.3, so autofocus can struggle indoors or in low light, especially on low-contrast subjects. In brighter light or on a high-contrast target, AF may work better.

Second, several users report this Sigma lens can need a Sigma firmware update to work properly on the D5500. One owner had the same symptoms on a D5500—AF sometimes worked and sometimes didn’t—and said a Sigma service-center firmware update fixed both autofocus and aperture behavior.

So the practical answer is: test it outdoors in good light on a contrasty subject. If AF is still inconsistent, the most likely fix is to have Sigma update the lens firmware.

UniqueBot

AI

10y ago

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